Electric signaling apparatus



May 5, 1931. B. AMES 1,804,195

ELECTRI C S IGNALING APPARATUS Filed Aug. 25, 1926 fizz/e27" .zafler 124 7726.? y/ z-Mw VN/ Q? Patented ay 5, 193i BUTLER AMES, F LOWELL, MASSACHUSETTS ELECTRIC SIGNALING APPARATUS Application filed August 25, 1926. Serial No. 131,380.

This invention relates to improvements in an electric signaling device such as an electric horn and in certain aspects presents improvements over the disclosures of my prior 6 application No. 94,726, filed March 15, 1926.

It is now common in this art to provide diaphragms or thin membranes of resilient material which are fixed at their edges and have their central portions secured to an ex tension of the armature of an clectromagnet, the magnet being rapidly energized or de energized by an alternating current, or more often by a make-and-break mechanism in a direct current circuit. Such a make-andbreak is usually effected by interposing a contact carrying member in the path of the vibrating armature so that when the armature has been attracted to a position close to the electromagnet the current is automatically broken and the resilient diaphragm,

which may be aided by another spring element, will serve to move the armature in the opposite direction permitting the circuit again to be closed, the magnet again to be energized and the vibratory action repeated.

In order to provide a satisfactory note or tone for the horn 0r signaling apparatus it is desirable to have the frequency of vibration rather high, consequently the making and breaking of the electric circuit must oc* cur with considerable rapidity. Such a condition results in appreciable pitting or burn ing away of the contact points, particularly when metals suited to low-cost production are used.

A salient feature of the present invention relates to the provision of contact carrying means for make-and-break apparatus of this 7 general type in which the contacts may be supported in a convenient manner and at a minimum cost, and yet in which the contacts may be relatively adjustable in a convenient manner to compensate for the wear and pitting of the contact points or areas, for fa- 5 tigue in the vibrating spring, or for adjustment of the armature itself.

Another feature of the present invention pertains tothe provision of simplified means for detachably securing the cover for the signal actuating mechanism in place, whereby access to the mechanism and adjustment thereof may be facilitated and cost of production may be lowered. This invention also. provides a 'baflie plate construction which comprises an improvement over the analogous arrangement disclosed in my above-identified prior application.

The above and further objects and advantages of the invention will become apparent to those skilled in the art upon a reading of the subjoined description and claim in conjunction with the accompanying drawings, in which:

Fig. 1 is an end elevation oi one embodiment of the invention with the cover removed;

Fig. 2 is a section on line 2-2 of Fig. 1 showing the cover in place;

Fig. 3 is a detail sectional view on line 33 of Fig. 1 showing a portion of a tool inserted to adjust the contacts in relation to each other.

Fig. 4 shows an enlarged detail view of a portion of the diaphragm with the modified form of washers shown in Fig. 5 mounted thereon; and

Fig. 5 shows a modified form of washer of resilient material in which the washer is bent at the periphery so as to permit holding the Washer in pressure contact with the surface on which it is mounted.

Referring to the accompanying drawings, the numeral 1 designates a resilient diaphragm which is adapted to be vibrated in order to generate sound waves and which is connected at its periphery by suitable fastening means such as the bolts 2 to a sounding box 3, which is provided with an outstanding horn 4, and to a circular base plate 6 which has its central portion dished away from the membrane as designated by the numeral 7 The plate 6 is comparatively stifi and rigid and serves to support the electromagnet- 10 by means of the U-shaped bracket 11 (Fig. 1). The mechanism may be provided with a suitable detachable cover 13 secured in place by a single fastening such as screw 1ft threaded into the core of magnet 10, the wall of sounding box 3 being extended to comprise an annular flange 9 which is adapted telescopically to engage the periphcry of the cover.

The electromagnet 10 may be energized by current received through the lead 15 and returning from the magnet through lead 16 to the make-and-break mechanism. A suitable armature 20, preferably comprising a disc, is normally located in slightly spaced relation to the core of the magnet 10 and is provided with an extension 30 which may be secured to the central part of the membrane 1 in any conventional manner as by being threaded into the collar 38 secured thereto. Preferably a rigid baffle plate 8 may be secured to the extension of the armature at the other side of the membrane 1 and within the sound box 3. Bafiie plate Sis composed of a pair of thin metallic shells, adjoining peripheral edges of which are in firm telescopic engagement and the central portions of which are held in rigid spaced relation by ,a suitable tube 34 which receives extension 30 of the armature. The end of this extension is provided with a nut 36 to hold the baffle plate in place and also with a slot 31 to receive a screw driver to permit adjustment of the armature in relation to the magnet. The hollow baffle plate 8 is a light yet rigid member which is adapted to vibrate with the central portion of the diaphragm and accentuate the noise produced by the device.

The make-and-break mechanism comprises a normally fixed contact 25 and a vibratory contact 26. Preferably the fixed contact 25 is located upon the plate 27 which is separated from base plate 6 by a thin sheet 24 of insulating material such as fibre. The plate 27 is preferably composed of ductile metal and is electrically connected to the lead 16. The

contact 26 is supported upon the resilient spring member 28, which is spaced from the member 27 by another sheet or spacer 29 of insulating material. Both of these contact supporting members are secured to the base plate 6 by a washer or the like 39, spaced from the member 28 by insulating material, and a pair of screws 32 passingthrough the superimposed plates and layers of insulating material and holding them to the base plate 6. In order to insulate the screws from the metal plate 27 suitable sheets of insulating material may be located about their shanks while their ends are threaded into their base plate 6. The plate 6 is provided with a suitable opening designated by the numeral 35 and located beneath the contact carrying plate 27 to permit ready access thereto.

It is obvious that in the operation of the device the end of the resilient plate 28 will normally lie in the path of the oscillating armature 20 and that attraction of this armature by closing of the magnet circuit will serve to move the contact 26 away from the contact 25 and break the circuit, whereby, the magnet becoming de-energized, the resilience of the diaphragm 1 will draw the arma ture back to its original position or beyond, permitting the spring 28 to return the contact 26 to its normal position in engagement with contact 25, closing the magnet circuit, re-energizing the magnet, causing the armature again to be attracted toward the magnet and thus repeating the vibratory action in rapid sequence. 'The metal support 27 may be bent by the interposition of a suitable tool T thereunder as illustrated for example in Fig. 3 so that it may be brought up into closer engagement with the contact 26 in its normal position to compensate for wearing or pitting of the contact areas or for fatigue of the spring 28 or for adjustment of the armature toward the magnet. Obviously such an adjustment maybe made without removing the contact members, disturbing the insulating, or in fact doing anything but removing the outer cover and inserting a suitable tool beneath plate 27 Such an arrangement of the-make-and-break mechanism not only provides a simple and inexpensive means of supporting it, but a simple and foolproof method of adjustment when the same is desirable. Obviously, if the ductile plate 27 is bent too far, or if it is desired for any reason to move it away from the spring 28, such a proceeding may be followed with almost equal ease. However, during normal use of the device it is more often necessary to bring the contact points nearer together as has :Teen explained above and as illustrated in The contact points are preferably of silver although other material may be used, such as tungsten, or one silver and one tungsten point might be used. It has been found, however, that silver points serve to reduce arcing during making and breaking, and thus increases the life of the contact points.

In order to amplify or increase the sound from the horn, I may employ one or more reinforcing washers or springs upon the diaphragm 1. I preferably employ two large washers 40, 4.1 upon each side of the diaphragm adjacent thereto and superpose on the washers two smaller washers 42, 43 as shown in Fig. 3 of the drawings. The washers are of resilient or spring material and the peripheries thereof may be curved or bent inward (see Fig. 5) so as to be in pressure or resilient contact with the adjacent surface, whereby during the vibration'of the diaphragm the washers will vibrate synchronously and assist in the tone production in addition to giving support to the dia phragm to prevent its cracking from the strain of repeated vibration. By the use of a series of reinforced washers in this manner a thinner material may be used for the diaphragm and a greater amplitude of vibration is produced, resulting in a larger volume of sound than may be obtained with a single diaphragm. The reinforcement of the diaphragm at the central portion, which is subjected to the greatest movement or vibration, permits the high periodicity of vibration which is necessary for the production of a suitable tone and also permits the carrying of the load of the armature 520 and the baffie plate 8 without injury to the diaphragm,

By threading the armature post 30 forwardly or-rearwardlythrough the nut 36 and the nut or sleeve 45 of the collar 38 disposed in the openings in the diaphragm 1 and the diaphragm washersor disks (Fig. 2) the position of the armature relative to the diaphragm may be adjusted. The flange or shoulder 46 of the collar 38 which overhangs the rear washers serves as a part of the means for clamping the washers, diaphragm and baflie together, and the lower end of said nut or sleeve constitutes a shoulder 47 to limit the degree of clamping of the washers against the diaphragm depending upon the length of the spacer portion 48 between the two shoulders. (See Fig. 4.) The upper and lower disks of the baffle are preferably joined integrally by the tube 34 surrounding thepost 30 as shown in broken lines in Fig. 2 to,

form a rigid but light bafile.

By the use of a baffle plate 8 in the form of a cone having a large angle at its apex, as

shown in Fig. 2 of the drawings, adjacent, to

the bell flange 3, the sides of which subtend a smaller angle,'an outwardly flaring chamber or annular space 44 is formed providing free egress of the sound waves from the baffle or place where they are generated, or in other words, a resonance chamber is produced from which the sound waves may be emitted in a free diverging path into the atmosphere. In this form of the device the sound emission is principally from the baffle 8, but it is to be understood that the baffle may be made smaller if desired so that a substantial part of the sound emitted may come from the diaphragm 1; and in this case it is particularly desirable to employ the modified form of reinforcing member shown in Fig. 5 in order to avoid the production of tone having a different period of vibration from that of the diaphragm. In'the form of reinforcing member shown applied to the diaphragm in Fig. 4, the peripheries of the disks are in pressure contact with the diaphragm or the underlying reinforcing member whereby the disks can vibrate only with the same frequency as the diaphragm 1 and will not produce any tone except that corresponding to the period of vibration of the dlaphragm, and a purer tone is thus produced than would be obtained with the form of washer or reinforcing member shown in Fig. 2. It is to be understood that various changes or modifications may be made in the form of 'my invention as may be apparent to those skilled in the art without departing from the spirit or scope thereof as defined in the claims.

I claim:

1. Electric signaling apparatus comprising a Vibrating member, mechanism for vibrating the member at one side thereof, a horn element at the other side thereof, a sounding box at the end of the horn element adjoining the member, and a hollow metal bafiie plate therein rigidly secured to the member and adapted to vibrate therewith, said baffle plate comprising a pair of sheet metal members with marginal portions joined and central portions maintained in rigid spaced relation by a connecting element.

2. Electric signaling apparatus comprising a vibratory disk member rigidly held at its periphery and adapted to vibrate at the central portion thereof, amechanism for vibrating the member, a vibratory conical baflie plate connected to said member, the sides of the said plate extending toward said member so as to form a large angle at the apex of the cone, a resonance chamber around said baiiie, the sides of which diverge toward said member at a lesser angle than the sides of the said bafile plate, whereby an outwardly flaring resonance space is formed for the emission of sound waves from the said bafiie plate.

3. Electrical signaling apparatus comprising a casing, a diaphragm mounted in the casing, means for vibrating the diaphragm including a member extending through an opening therein, and a disk clamped against the diaphragm around said opening, the disk being curved toward the diaphragm at its outer margin so that the diaphragm is firmly engaged at the peripheral edge of the disk.

4. Electrical signaling apparatus comprising a diaphragm, a post extending through an opening in the diaphragm, disks engaging the opposite sides of the diaphragm around said opening, and a collar including a spacer extending through the diaphragm and disks around said post, said collar clamping said disks to the diaphragm, said spacer serving to limit the degree of clamping.

5. Electric signaling apparatus comprising a casing, a diaphragm mounted in the casing, means for vibrating the diaphragm including a member extending through an opening therein, a disk clamped against each side of the diaphragm around said opening and a smaller disk clamped against each of said disks, each of said disks being curved toward the diaphragm at its outer margin so that the diaphragm and disks make firm contact at the margins of the disks.

6. Electrical signaling apparatus comprising a diaphragm, a post extending ing said disks to the diaphragm including a spacer extending through the diaphragm and disks around said post, a shoulder overhanging the disk on one side of the diaphragm, and another shoulder on the other side of the diaphragm, said spacer limiting the degree of clamping.

7. Electrical signaling apparatus comprising a diaphragm having an opening,

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1s s engaging opposite sides of the diaphragm with openings aligned with said opening, said disks being curved toward the diaphragm at their outer margins to make firm contact with the diaphragm at their peripheral edges, a post extending through said openings, a sleeve threaded on said post in said openings, a battle fitting over the post in front of the diaphragm, means for clam ing the diaphragm, disks and baflie together including a flange on said sleeve overhanging the rear disk, and means for actuating the diaphragm mounted on the rearend of said post, the latter means and diaphragm being adjustable toward and from each other by threading the post through said sleeve.

8. Electrical signaling apparatus comprising a diaphragm having an opening, disks engaging opposite sides of the diaphragm with openings aligned with said opening, said disks being curved toward the diaphragm at their outer margins to make firm contact with the diaphragm at their peripheral edges, a post extending through said openings, a sleeve threaded on said post in said openings, a battle fitting over the post in front of the diaphragm, and means for clamping the diaphragm, disks and hafiie together including a flange on said sleeve overhanging the rear disk and a nut threaded on said post in front of the bafie.

9. Electrical signaling apparatus comprising a diaphragm having an opening, a post extending through the opening, and a bafile fitting over the post in front of the diaphragm, the baflie comprising two disks of sheet metal joined at their peripheries and spaced apart at the middle and a tube holding the central portions; of the disks in rigid spaced relation.

10. Electrical signaling apparatus comprising a diaphragm having an opening, a post extending through the opening, and a hafiie fitting over the post in front of the diaphragm, the bafile comprising two disks of sheet metal joined at their peripheries and spaced apart at the middle.

Signed by me at "Lowell, Massachusetts, this twenty-sixth day of June, 1926.

v BUTLER S. 

